another another point to consider is that an experiment on a group of subjects must be designed so that all subjects receive the same experience and can be compared so this necessity can result in a design that's not the best one for all your subjects so during experiment on behavior modification an experimenter may discover that a subject does not respond to a reinforcer that has worked on previous subjects so if the design is a single subject one the experiment can be modified on the spot by switching reinforcers or by alternating the instructions and another problem can that can be solved by a design modification is when a large change occurs in the participants behavior that the experimenter suspects is caused by an outside event rather than the experimental manipulation I mean think about it if you were conducting a study and then coronavirus took place that might affect the stress levels of participants the behaviors that they take the accessibility to treatment conditions etc so the experimenter can immediately switch the conditions to see if the behavior changes correspondingly a group experiment however would call for continuing all participants in the same procedure and hoping that the outside events would essentially cancel each other out so this would be a design limitation of a group study so we should also mention some disadvantages of the single subject approach if there were none after all no multiple subject experiments would ever be done because it's a lot easier to do single subject research that is to do groups group research so first some effects are small relative to the amount of variability in the situation it may be impossible to control the other sources of variability sufficiently to observe the experimental effect in one subject this is why modern statistical methods were developed in the first place the only way to decide if having been abused as a child causes adults to be child abusers themselves is to compare large groups of individuals so it's no surprise that group experiments and statistical analysis are discussed together so often statistical procedures for analyzing single subject data are not as well developed second some experimental effects are by definition between subjects effects so you're looking at different subjects it's impossible to have a participant who simultaneously receives two opposite sets of instructions in a social psychology experiment or who is taught the same material by two different methods without them retaining the first method so you need to have different participants to compare so this is where it becomes more advantageous to have different groups versus different individuals so when you're using a group design you compare one group of subjects against another or a group of subjects in one condition against the same subjects at another condition so the assumption that the groups were equal before the treatment is the basis of your attributing the effect the manipulation rather than to something else so this assumption can be tested by statistically analyzing the differences between groups so when you have only one subject you have to use a different strategy or the outcomes between conditions and that strategy is to compare the behavior that occurs before and after the introduction of the experimental manipulation that the behavior before the manipulation must be measured over a long enough time span to obtain a stable baseline against which the later behavior will be measured so the baseline is it really serves two purposes it's the it measures the current level of behavior and it predicts what the behavior would be in the future if no treatment were administered the valuation of a that's a fact can only occur baseline measurements shows the behavior to either be remaining at the same level or changing in the direction that is opposite to the predicted treatment effect so suppose you want to measure the effectiveness of a treatment for anorexia nervosa a disorder characterized by voluntary starvation you would need to measure the patient's weight and food intake for a period of time before initiating treatment so that you could show that the weight was stable and that the patient had not begun gaining weight spontaneously how long this baseline measure should be continued is to say this is one of the areas where you'd run into potential problems the judgment of stability is subjectively however the experiment would be useless unless it was evident that the patient had not begun gaining weight before treatment so a declining baseline may be acceptable because the treatment in this example is expected to is expected to cause an increase in behavior so a decrease in weight in the absence of treatment is not unusual for patients with anorexia nervosa because they're not getting their required flooring intake so a weight loss would constitute an acceptable baseline for comparison with treatment so this example illustrates another consideration for obtaining baseline measures sometimes the existing condition is harmful to the subject or even life-threatening as as in this example so the goal of a stable baseline may be overridden by other factors so that's important to consider as well so if you simply measure the baseline behavior usually referred to as or denoted by a and single subject designs and injury as a treatment usually called B it's called a comparison design or an AV design so in in 1996 there was a paper that reported cases of phantom pain that were treated effectively with the AV design so in this paper the 63 year old woman in this study have lost her leg below the knee yet was still experiencing pain sensations from the part of the leg that had been amputated so that was that was the baseline condition that they were looking at during a single session of the proposed treatment the woman was taught a strategy for deferring her attention from the pain so that was the treatment condition after the treatment the woman reported that the pain had substantially decreased but can we be sure that the treatment really led to pain relief well no but the difficulty with VAV design is that you will not know whether other variables that may have coincidentally changed at the same time that the treatment was administered actually produced the change in behavior so here's the potential confounding variables have a big deal in fact you would have the single participant equivalent of the quasi-experimental design called the one group pretest post-test design so you know that that could be tricky but if you're interested in this paper it's a 1996 paper by March Ian Sten R John Johnson and Karen Fisher and it is an interesting read but it also introduces a lot of questions as to what you know whether the actual treatment effect was what they were seeing which is one of the issues with this so although an a/b design may be appropriate for some clinical situations the argument that the treatment is the cause of the change is considerably strengthened if the treatment is withdrawn after a period of time and the behavior shows a return towards the baseline so this use of treatment withdrawal as part of an experimental condition is often referred to as an ABA design so two principal problems are associated with the ABA design first the effect of the manipulation may not be fully reversible right just because you remove a treatment it may not show the effect that you're looking for so if the treatment were a lesion of the brain that causes obesity clearly would be impossible reverse that and if a learning procedure causes a more or less permanent change in a participants behavior that - really wouldn't be reversible the second problem with ABA designs is that you may want to leave the participants in the new condition rather than returning them to their original state so treatments involving weight control phobias also behaviors are typical examples in which it would really be unethical and definitely undesirable to withhold treatments until the patient returned to their original state in such cases the experimenter may withdraw treatment temporarily before the behavior change has reached the desired level but after the behavior shows some reversal of the trend towards improvement he or she would reinstate the treatment in any case experimenters in behavior modification seldom and an experiment with the baseline or draw condition rather they reintroduce the treatment to produce the maximum benefit for the client so you really you know have to think about the effects of these single subject designs especially if you're if you're talking about introducing a new form of a treatment to treat an issue that a person's really suffering from so then we also have a B a B design so in the examples I just discussed the treatment was repeated after the withdrawal phase and to leave the participant with the full benefit of the training so this repetition of treatment also has the advantage of providing another opportunity to evaluate the effect of the treatment and its reliability so this kind of ABA design experiment in which treatment is repeated is actually called a B a B or replication design so repeated presentation with all of a variable confused strong evidence for the validity of the independent variables fact so anybody who watches a pigeon who's been trained in a in a skinner box respond to the presence of a light and not respond to its absence would be impressed by the control of the light exerts over the animals behavior the light appears to turn the behavior on and off by a switch so this would be an example of this design so another an important rule of a single participant or single participant research in general is to vary only one thing at a time so if two variables are changed simultaneously it's impossible to decide whether the change in behavior was caused by one or the other or by two together so on occasion it may be important to evaluate the effect of two or more different treatments to assess which one would be the most effective so for a study done in 2000 by Michael Mazzoni and Stephanie our tennety they were interested in ways that therapeutic rehabilitation sessions could be more effective for people with brain injuries so many of the therapeutic activities were frustrating or difficult for participants and brain injury patients often have difficulty in remaining on task and so the researchers wondered whether or wondered which of the three different treatments would be most effective in helping patients stay on task allowing the patient to earn short breaks giving them praise for cooperation or displaying the progress of rehabilitation so to meet the requirement that only one variable at a time be changed in single participant design they alternated the treatments across sessions with a 15 year old male patient in a speech therapy session so this method is called an alternating treatments design behavior was observed during the first baseline phase then three treatments were administered the patient had randomly chosen one of the three alternating treatments in each session and if a strict alternation had been followed then the type of treatment would have been confounded with the time of day or day of week so it was important that the treatments were randomly allocated it's possible that attention might be lower in the afternoon that in the morning for example so the patient was told which of the three treatments or Consequences would be in effect for each session before it began the results showed that allowing the patient to earn short breaks was the most effective of the three treatment so you can see how this would be a useful design for certain types of single subject studies so the first part of the alternative treatments design answers the question of which is the more effective treatment it doesn't however necessarily show that the behavior change was the result of that treatment as the baseline may have been changing anyway so evaluating whether the treatment caused the behavior changes would have required some sort of repetition of the design one way would have been to remove all three treatments than measuring baseline performance for a period of time when the baseline was again stable the more effective treatment could be reintroduced so essentially this design is similar to the AV AV design with the one added piece that the more the more than one type of treatment is administered during the first non baseline condition however the researchers didn't want to withhold treatment from the patient because they were afraid therapeutic gains may be reversed instead they continue to implement the most effective treatment earning short breaks from speech therapy somewhat like changing criterion designs so they gradually increase the amount of time the patient wouldn't have to concentrate in order on a break from two minutes all the way up to thirty minutes so another effective way to demonstrate that the manipulation caused the behavior change is to reintroduce the manipulation at different times for each of several different behaviors to see if the onset of the behavior change coincides with manipulation for example suppose a researchers trying to determine if rewarding a child who has intellectual disability for doing certain personal tasks is a fact that so if the researcher begins to reward tooth brushing facial face washing and washing and air calming all at the same time it's possible that the presence of the experimenter the attention received or a spontaneous decision to turn over a new leaf was responsible for the change so the researcher however could begin rewarding only tooth brushing the first week tooth brushing and face washing the second week and so forth until after four weeks all behaviors were being rewarded this sequence would make it implement would make it possible to see whether the increase in behavior coincides with reward so this design is known as a multiple baseline design the separate in experimental baselines may be different behaviors in the same individual as the example I just gave or the same behaviors and different individuals a third possibility is to test the same behavior in the same individual but in different behavior settings so an example of this last approach will give it a second but multiple baseline designs are especially useful if expected behavior change is irreversible so in a study done by Singh Dawson and Gregory in 1980 they used a multiple baseline design with withdrawal of treatment to stop an 18 year old female with found intellectual disability disability from hyperventilating this problem in which a person reads too deeply can have serious medical consequences so several treatments including reprimand medication had been attempted on the participant really without any success so the researcher has decided to punish episodes of hyperventilation by briefly presenting ammonia with so smelling salts if you've ever experienced that if you've ever fainted or or you know been feeling woozy it is a very powerful noxious experience yes I wouldn't call it torturous but it definitely will distract and deflect from one's reaction if they're having one so smelling salts and ammonia were presented every time the participant hyperventilate so the design was a multiple baseline design with the withdrawal of treatment as a test probe baseline recordings were made for five days in each of four different settings so class room the dining room bathroom or in experimental sessions lasted two hours per day so 30 minutes each in each of the four settings during this time all instances of hyperventilation were recorded but not punished then the baseline recordings were continued in three of the settings and punishment was administered to any episodes of hyperventilation that occurred in the classroom after five more days punishment was instituted for episodes that occurred in the dining room as well as in the classroom and baseline reporting continued in the bathroom and living room after five more days punishment was extended to the bathroom and after another five days to the living so the data from this experiment it really indicated that the frequency of hyperventilation did not decrease in any of the baseline conditions in each situation when punishment was initiated however hyperventilation decreased dramatically again and this kind of punishment I mean it's extremely powerful extremely distracting so it it kind of took her out of the state that they were trying to take her out it so after punishment I can have been continued for five days in the last the punishment was withdrawn but the episodes of hyperventilation were still recorded up to the participant began hyperventilating again in all situations but ceased abruptly when punishment was reinstated after 15 more days of punishment for any instance of hyperventilation in the four settings the procedure was generalized instead of having one experimenter administer punishment in the four settings during a two-hour session all nurses in the ward were to administer punishment whatever they observed hyperventilation in any setting during eight-hour day so this practice was instituted to consolidate and maintain the previous games so this study illustrates how to test the effectiveness of an experimental manipulation on a single participant in an unambiguous manner because the manipulation was instituted at four different times in four different settings the researchers would otherwise have had to use for all of different alternative hypotheses to account for the decrease in hyperventilation after the increase in hyperventilation that occurred followed the removal of punishment and the abrupt decrease when punishment was reinstated to give further evidence of the effectiveness of treatment so another way of showing the manipulation caused the behavior change is to change the criteria for reward over time so after a baseline measurement a reward can be given for meeting a lacks criteria of the behavior so after the behavior stabilizes at that level the criterion can be raised until the behavior stabilizes again and so forth if the behavior begins to change after each change in the criterion then the conclusion that the reward is the cause of the improvement is is rather convincing so suppose that a child is unable to sit still in class a teacher may reward the child for sitting still to five minutes or for five minutes at a time I should say until the performance becomes stable then the criterion may be set at ten minutes later 15 minutes and so forth the behavior at each criterion becomes the baseline against which to evaluate the effect of the manipulation of the next criterion so like the multiple baseline design a what's called changing criterion design is useful when behavior changes irreversible or when the return to the initial baseline is not desirable as in a case involving the reading skills of a man with schizophrenia named Craig and this is in a study done by Skinner Skinner and Armstrong in 2000 and notes it's not the same Skinner so Craig was able to read at the beginning of the experiment but only got a read on average one page per day so that's not that great they wanted to increase the amount of pages rent per day and so the increase of the amount of pages read per day what or the number of pages read per day was the dependent variable and the opportunity to earn a soft-drink was the treatment so he was being rewarded for reading more pages per day Craig had demonstrated during a baseline that he could read one page per day so this was set at the initial criterion level and after Craig achieved the criterion level three days in a row the criterion would be raised by one page per day so at the end of the program Craig was reading on average eight pages per day and a behavior change persisted for about seven weeks out to the program of it so it was effectiveness work but it was affected for at least a period of time so that's all we have for today's lecture on single subject research design as always make sure to answer the discussion questions posted for this week please be mindful of the part to prompt for the second part of the research paper a few notes on that when you are submitting your research paper the second part it should be submitted as one continuous document with the part one research paper that is you're not just submitting the second half just like you submitted just the first half for the part one assignment it's gonna be one big paper so the idea for this assignment was that you would have a large research paper where the first component would be the literature review the research questions and the hypotheses then the references you have so far the second part is going to be your proposed methods your anticipated results and then a discussion section that ties everything together and so in that discussion section you're going to be following the same order of the introduction of information you had in your literature review in that introduction section with all of the information that you know when you talked about research that still need to be done research that kind of led you to where you are seeing those data points as things to address your discussion how your proposed study would address the information you've organized in the literature of you so if you have any questions about how to do this please feel free to reach out email me I'd be happy to guide you through the process discussion sections are often a lot more fun to do than the introduction because you've already done the background research and essentially you're addressing point by point what had to be done and how your study did it and if your study didn't do it how your study contributed to answering that question and then at the end of the discussion and this is important you should have suggestions for future research based on the research that you're proposing doing because nobody is going to be proposing a topic that addresses everything usually when we answer some questions it has the potential to bring up more questions in the future and so you're keeping the sign to the cross that's a by suggesting future research ideas so be sure to organize it that way also do the best you can to to resolve my comments that I have made on your papers so just be sure to integrate that in whatever way possible if you have any questions about the comments that I've made feel free to reach out to me and and to email me and we can discuss that further alright guys take care have a great week and I'll look forward to reading your discussion posts